The present invention relates to a thermal transfer recording medium for use in thermal transfer recording devices such as thermal printers and facsimile terminal equipment. More particularly, the present invention relates to a thermal transfer recording medium for the formation of a multi-color or full-color image by the superimposing transfer of plural different color inks.
There has hitherto been conducted the formation of a multi-color or full-color image wherein plural different color inks are superimposingly transferred one on another on a receptor by means of a thermal transfer printing or the like to form a multi-color or full-color image involving a region developing a color by virtue of subtractive color mixture. As the thermal transfer recording medium for such a method there has been widely used one having the structure wherein a release layer comprising a wax as a main ingredient is interposed between a foundation and a color ink layer to improve the transferability.
When plural different color inks are superimposingly transferred to form a multi-color or full-color image on a receptor by use of the above-mentioned thermal transfer recording medium, the release layer comprising a wax as a main ingredient would exist on the top of first color ink dots formed on the receptor, thereby causing the problem wherein second color ink dots are not satisfactorily superimposed onto the first color ink dots due to the presence of the release layer on the first color ink dots.
In view of the aforesaid problem of the prior art, it is an object of the present invention to provide a technique wherein in the case of forming a color image by use of a thermal transfer recording medium having the structure wherein a release layer comprising a wax as a main ingredient is interposed between a foundation and a color ink layer, second color ink dots are satisfactorily transferred onto first color ink dots.
This and other objects of the present invention will become apparent from the description hereinafter.
This is a continuation of copending, commonly-assigned U.S. patent application Ser. No. 09/092,186 filed Jun. 3, 1998, now abandoned. The present invention provides a thermal transfer recording medium for forming a color image by superimposingly transferring plural different color inks, comprising a foundation and a color ink layer provided on the foundation, and a release layer comprising a wax interposed between the foundation and the color ink layer,
wherein the thickness d1 of the release layer for a first color and the thickness d2 of the release layer for a second color satisfy the relationship represented by formula (I):
d1 less than d2 less than 2.0 d1xe2x80x83xe2x80x83(I)
In an embodiment of the present invention, the thickness d1 of the release layer for the first color is from 0.05 to 0.7 xcexcm.
In another embodiment of the present invention, plural different color ink layers are disposed in a side-by-side relation on single foundation with respective release layers intervening between the foundation and ink layers.
In still another embodiment of the present invention, plural different color ink layers are disposed on separate foundations with respective release layers intervening between the foundations and ink layers.